"Virtualizing the operating system and running it from a
removable storage device has its advantages but it will not pull
you out of a jam in case the host operating system is damaged.
"If you plan on rescuing data off a Windows-running machine or
if you simply feel the need of an alternate operating system then
Linux seems to be the solution. There are plenty of distros to
choose from, with Ubuntu reigning over them through its ease of use
and flexibility to run both installed on your machine as well as
from a live CD."